Define ozone?

Question

how is ozone produced in the lower atmosphere? what harmful affects does ozone have on humans?

Answer 1

Since ozone comes from chemical reactions among ozone precursors in the atmosphere, the sources of ozone are actually the sources of the precursors.  Ozone precursors come from

Fuel combustion and evaporation associated with cars, trucks, buses and equipment;

Fuel combustion and evaporation associated with large stationary sources such as power plants, oil refineries, and factories;

Fuel combustion and evaporation from small stationary sources such as gasoline dispensing facilities, print shops and others;

Organic compound evaporation from consumer products such as paints, cleaners, and solvents; and

Fuel combustion and evaporation from off-road engines in aircraft, trains, construction equipment, agricultural operations, and lawn and garden equipment.

Unhealthy ozone levels occur when precursor emissions react in the presence of sunlight, warm temperatures and light winds.  Emissions from the above sources in the winter do not typically produce high ozone levels due to diminished sunlight and cooler temperatures.  

Ozone can irritate the respiratory system at levels often found in many cities during the summer months. It not only affects people with existing breathing problems, but also can affect healthy children and adults. Persons especially sensitive to ozone exposure are the elderly, infants, children, asthmatics, chronic respiratory patients, pregnant women, smokers, persons with a history of chest discomfort or respiratory allergies, and persons with lung cancer, cardiovascular disease or immune system deficiency.

At low levels, persons sensitive to ozone may experience irritation of the eyes, nose, sinuses, throat and lungs resulting in watery eyes, runny nose and coughing. At higher levels, ozone can cause chest tightness, shortness of breath, pain when breathing deeply and wheezing. Other less common symptoms are blurred vision, headache, nausea, vomiting and fatigue. Ozone also appears to make the lungs more susceptible to bacterial infections.

The odor of ozone is noticeable at low levels. As the level of ozone increases, the ability to smell it may decrease. This is especially true when persons are frequently exposed to it. No odor and fewer symptoms may falsely give the impression of reduced exposure to ozone, even though further damage to health may be taking place. Children may suffer lung irritation but not notice or complain about symptoms. Because children breathe more rapidly, they inhale more pollutants per pound of their body weight than adults.

Healthy individuals who exercise while ozone levels are elevated can experience reduced lung function leading to chest pain, coughing, wheezing and congestion. During exercise, air intake increases and air is drawn more deeply into the lungs. A study of longtime Los Angeles residents, who experience the most frequent outdoor ozone problem in the nation, found that the group had a higher than expected loss of lung function.